Coat a large pot with non stick cooking spray and sauté` onion, celery, bell pepper, and garlic until tender. Add corn, tomatoes with green chilies, tomato paste, shrimp, crabmeat and seasonings. Mix everything together. Add chicken broth and bring to a boil. Lower heat to a simmer and cook for 1 hour, adding water as needed to keep the consistency soupy. Add green onions and simmer for 15 more minutes.